{
  "protocolVersion": "0.3.0",
  "name": "Mailsnail",
  "description": "Send real, postmarked US physical mail — letters, certified letters, postcards. No signup: pay-per-piece via Stripe Shared Payment Tokens over the Machine Payments Protocol (HTTP 402). Interact via the Mailsnail MCP server (npx -y mailsnail, stdio) or the REST API at https://api.mailsnail.dev (OpenAPI: https://mailsnail.dev/openapi.json). This card is discovery metadata; the service speaks MCP and REST rather than A2A JSON-RPC.",
  "url": "https://api.mailsnail.dev",
  "provider": {
    "organization": "Mailsnail",
    "url": "https://mailsnail.dev"
  },
  "version": "0.6.0",
  "documentationUrl": "https://mailsnail.dev/llms.txt",
  "capabilities": {
    "streaming": false,
    "pushNotifications": false
  },
  "defaultInputModes": [
    "application/json"
  ],
  "defaultOutputModes": [
    "application/json"
  ],
  "skills": [
    {
      "id": "verify_address",
      "name": "Verify address",
      "description": "USPS CASS validation. Free. Returns deliverability + normalized address.",
      "tags": [
        "mail",
        "address",
        "validation"
      ]
    },
    {
      "id": "preview_letter",
      "name": "Preview letter",
      "description": "Proof PDF + exact price WITHOUT charging or mailing. Returns proof_url and a draft_id to confirm with send_letter.",
      "tags": [
        "mail",
        "letter",
        "proof"
      ]
    },
    {
      "id": "send_letter",
      "name": "Send letter",
      "description": "Mail a physical letter to a US address from plain text (rendered server-side) or a PDF URL. extra_service 'certified' for legal/compliance mail. $1.50 first-class, $9.00 certified.",
      "tags": [
        "mail",
        "letter",
        "usps",
        "certified"
      ],
      "examples": [
        "Send a certified letter to this address with this notice text",
        "Mail a thank-you letter to my customer"
      ]
    },
    {
      "id": "send_postcard",
      "name": "Send postcard",
      "description": "Send a 4x6 / 6x9 / 6x11 postcard from a PDF. $1.00.",
      "tags": [
        "mail",
        "postcard",
        "usps"
      ],
      "examples": [
        "Send me a postcard that says hello"
      ]
    },
    {
      "id": "get_letter",
      "name": "Get letter status",
      "description": "Look up the status of a sent piece by id.",
      "tags": [
        "mail",
        "status"
      ]
    },
    {
      "id": "list_letters",
      "name": "List letters",
      "description": "Page through sent mail (Lob mode only).",
      "tags": [
        "mail",
        "status"
      ]
    },
    {
      "id": "cancel_letter",
      "name": "Cancel letter",
      "description": "Cancel a piece before it enters production. Windows are short and provider-specific.",
      "tags": [
        "mail",
        "cancel"
      ]
    }
  ]
}